Application of hydrogenation to low-temperature cleaning of the Si(001) surface in the processes of molecular-beam epitaxy: Investigation by STM, RHEED and HRTEM

Structural properties of the clean Si(001) surface obtained as a result of low-temperature (470--650C) pre-growth annealings of silicon wafers in a molecular-beam epitaxy chamber have been investigated. To decrease the cleaning temperature, a silicon surface was hydrogenated in the process of a preliminary chemical treatment in HF and NH_4F aqueous solutions. It has been shown that smooth surfaces composed by wide terraces separated by monoatomic steps can be obtained by dehydrogenation at the temperatures > 600C, whereas clean surfaces obtained at the temperatures < 600C are rough. It has been found that there exists a dependence of structural properties of clean surfaces on the temperature of hydrogen thermal desorption and the process of the preliminary chemical treatment. The frequency of detachment/attachment of Si dimers from/to the steps and effect of the Ehrlich-Schwoebel barrier on ad-dimer migration across steps have been found to be the most probable factors determining a degree of the resultant surface roughness.Comment: 8 pages, 8 figures; version accepted to J. Appl. Phy

Petro fabric characteristics of olivine from xenoliths, peridotites, and basalts (from Canary Islands, Kuznetsk Alatau and Yoko-Dovyren Massif)

This paper presents results of study of petro fabric specific characteristics of olivine from xenoliths, peridotites, and basalts (from Canary Islands, Kuznetsk Alatau and Yoko-Dovyren Massif

Sedimentary deposits and petrography of the basalts of the island of Tenerife of the Canary archipelago (Spain)

The article is devoted to the study of sedimentary deposits on the slopes of the Teide volcano and petrography of the volcanic rocks of the island of Tenerife of the Canary archipelago (Spain). A description of the sediments, which are presented on the island's territory, and an analysis of the features of the material composition of rocks are given

Experience of universities in practice-oriented training personnel for high-tech enterprises

Different options have been considered of work-based learning (WBL) in Russian and foreign universities. Special attention is given to the variant of PBL - project learning (PL) on training bachelors. Basic concepts and principles have been discussed dealing with the organization of PL developed by Aalborg University - one of the founders of this teaching technique. Тhe advisability is shown of organizing special courses of introduction to project learning in the first two semesters.peer-reviewe

Printing House of Ministry of Internal Affairs of Russian Empire in Mid-19th — Early 20th Centuries: structure, functions, personnel

The general characteristics of the government printing house that served the interests of Ministry of Internal Affairs in the middle of the 19th and the beginning of the 20th centuries, from the moment the printing house was created in 1836 until the 1910s, when the government was forced to join the struggle for public opinion. The staff of the printing house of the Ministry of Internal Affairs, its structure and changes in personnel and functions are investigated. It is shown that the outbreak of the First Russian Revolution accelerated the transformation of the printing house of the Ministry of Internal Affairs from an institution dealing with printing works on the document circulation of the Ministry of Internal Affairs into a structure that performs important functions in the ideological struggle for public opinion. It is proved that at the beginning of the twentieth century the priority direction for the printing house of the Ministry of Internal Affairs was the task of printing government newspapers “Government Bulletin”, “Russian State”, “Evening addition to the Government Bulletin”, etc. The difference between the servants and the workers of the printing house of the central state institution is emphasized. It is noted that if the servants of the printing house of the Ministry of Internal Affairs initially had the right to receive a social package, then the workers of the printing house had to earn this right

Impact of High-Temperature, High-Pressure Synthesis Conditions on the Formation of the Grain Structure and Strength Properties of Intermetallic Ni[3]Al

The impact of the preliminary load on 3Ni+Al powder mixture and the impact of the duration of the delay in application of compacting pressure to synthesis product under the conditions of continuous heating of the mixture up to its self-ignition on the grain size and strength properties of the synthesized Ni[3]Al intermetallide material have been studied. The grain structure of the intermetallide synthesized under pressure was studied by means of metallography, transmission electron microscopy and EBSD analysis, with the dependence of ultimate tensile strength on the grain size in the synthesized intermetallide having been investigated at room temperature and at temperatures up to 1000°С. It is shown that an increase in the pressure preliminarily applied to the initial mixture compact results in reduced grain size of the final intermetallide, whereas an increase in pre-compaction time makes the grain size increased. A decrease in the grain size increases the ultimate tensile strength of the intermetallide. The maximum value of the ultimate tensile strength in the observed anomalous temperature dependence of this strength exhibits a shift by 200°С toward higher temperatures, and the ultimate strength of the synthesized intermetallide at 1000°С increases roughly two-fold